Tasks done

Exercises.ru.md

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+# Упражнения
+
+## Итерирование циклами
+
+Руализуйте функцию `sum(...args)`, которая суммирует все свои аргументы, пятью
+разными способами. Примеры вызовов с результатами:
+```js
+const a = sum(1, 2, 3) // a === 6
+const b = sum(0) // b === 0
+const c = sum() // c === 0
+const d = sum(1, -1, 1) // d === 1
+const e = sum(10, -1, -1, -1) // e === 7
+```
+
+1. Цикл `for`
+2. Цикл `for..of`
+3. Цикл `while`
+4. Цикл `do..while`
+5. Метод `Array.prototype.reduce()`
+
+## Итерирование по двумерному массиву
+
+6. Найдите максимальный элемент в двумерном массиве
+```js
+const m = max([[1, 2, 3], [4, 5, 6], [7, 8, 9]]);
+console.log(m); // 9
+```
+
+## Итерирование объектов-справочников
+
+7. При помощи цикла `for..in` перебрать объект-справочник с датами рождения и
+смерти людей и вернуть справочник с продолжительностью их жизни. Например:
+```js
+const persons = {
+  lenin: { born: 1870, died: 1924 },
+  mao: { born: 1893, died: 1976 },
+  gandhi: { born: 1869, died: 1948 },
+  hirohito: { born: 1901, died: 1989 },
+};
+console.log(ages(persons));
+// {
+//   lenin: 54,
+//   mao: 83,
+//   gandhi: 79,
+//   hirohito: 88,
+// }
+```

Exercises/1-for.js

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 'use strict';
 
+// Use for loop and accumulator variable
+// to calculate sum of all given arguments
+// For example sum(1, 2, 3) should return 6
+
 const sum = (...args) => {
-  // Use for loop and accumulator variable
-  // to calculate sum of all given arguments
-  // For example sum(1, 2, 3) should return 6
+  let acc = 0;
+  for (let i = 0; i < args.length; ++i)
+    acc += args[i];
+  return acc;
 };
 
 module.exports = { sum };

Exercises/2-for-of.js

@@ -1,9 +1,14 @@
 'use strict';
+// Use for..of loop and accumulator variable
+// to calculate sum of all given arguments
+// For example sum(1, 2, 3) should return 6
 
 const sum = (...args) => {
-  // Use for..of loop and accumulator variable
-  // to calculate sum of all given arguments
-  // For example sum(1, 2, 3) should return 6
+  let acc = 0;
+  for (const num of args)
+    acc += num;
+
+  return acc;
 };
 
 module.exports = { sum };

Exercises/3-while.js

@@ -1,9 +1,15 @@
 'use strict';
 
+// Use while loop and accumulator variable
+// to calculate sum of all given arguments
+// For example sum(1, 2, 3) should return 6
+
 const sum = (...args) => {
-  // Use while loop and accumulator variable
-  // to calculate sum of all given arguments
-  // For example sum(1, 2, 3) should return 6
+  let accum = 0;
+  while (args.length !== 0)
+    accum += args.pop();
+
+  return accum;
 };
 
 module.exports = { sum };

Exercises/4-do-while.js

@@ -1,9 +1,18 @@
 'use strict';
 
+
+// Use do..while loop and accumulator variable
+// to calculate sum of all given arguments
+// For example sum(1, 2, 3) should return 6
+
 const sum = (...args) => {
-  // Use do..while loop and accumulator variable
-  // to calculate sum of all given arguments
-  // For example sum(1, 2, 3) should return 6
+  let accumulator = 0;
+
+  do {
+    accumulator += args.pop() || 0;
+  } while (args.length !== 0);
+
+  return accumulator;
 };
 
 module.exports = { sum };

Exercises/5-reduce.js

@@ -1,6 +1,7 @@
 'use strict';
 
-const sum = (...args) => 0;
+const sum = (...args) => args.reduce((acc, val) => acc + val, 0);
+
 // Use Array.prototype.reduce method
 // to calculate sum of all given arguments
 // For example sum(1, 2, 3) should return 6

Exercises/6-matrix.js

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+'use strict';
+
+// Use nested for loop to find max value in 2d matrix
+// For example max([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
+// should return 9
+
+const max = matrix => {
+  let maxVal = 0;
+
+  for (let row = 0; row < matrix.length; ++row)
+    for (let column = 0; column < matrix[row].length; ++column)
+      maxVal = (matrix[row][column] > maxVal) ? matrix[row][column] : maxVal;
+
+  return maxVal;
+};
+
+module.exports = { max };

Exercises/6-matrix.test

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+({
+  name: 'max',
+  length: [220, 300],
+  cases: [
+    [[[10]], 10],
+    [[[1, 2], [3, 4], [5, 6]], 6],
+    [[[-1, 1], [2, -1], [-1, 0]], 2],
+  ],
+  test: max => {
+    const src = max.toString();
+    if (!src.includes('for (')) throw new Error('Use for loop');
+  }
+})

Exercises/7-ages.js

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+'use strict';
+
+
+// Use for..in to calculate age for each person
+// For example ages({
+//   lenin: { born: 1870, died: 1924 },
+//   mao: { born: 1893, died: 1976 },
+//   gandhi: { born: 1869, died: 1948 },
+//   hirohito: { born: 1901, died: 1989 },
+// })
+// should return {
+//   lenin: 54,
+//   mao: 83,
+//   gandhi: 79,
+//   hirohito: 88,
+// }
+
+const ages = persons => {
+  const ages = {};
+
+  for (const persona in persons)
+    ages[persona] = persons[persona].died - persons[persona].born;
+
+  return ages;
+};
+
+module.exports = { ages };

Exercises/7-ages.test

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+({
+  name: 'ages',
+  length: [150, 190],
+  cases: [
+    [
+      {
+        lenin: { born: 1870, died: 1924 },
+        mao: { born: 1893, died: 1976 },
+        gandhi: { born: 1869, died: 1948 },
+        hirohito: { born: 1901, died: 1989 },
+      }, {
+        lenin: 54,
+        mao: 83,
+        gandhi: 79,
+        hirohito: 88,
+      }
+    ]
+  ],
+  test: ages => {
+    const src = ages.toString();
+    if (!src.includes('for (')) throw new Error('Use for..in loop');
+    if (!src.includes(' in ')) throw new Error('Use for..in loop');
+  }
+})

README.md

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 # Different implementation of iterations as a code abstraction
 
-[![Массивы, объекты, классы, прототипы](https://img.youtube.com/vi/VBMGnAPfmsY/0.jpg)](https://www.youtube.com/watch?v=/VBMGnAPfmsY)
+[![Массивы, объекты, классы, прототипы](https://img.youtube.com/vi/VBMGnAPfmsY/0.jpg)](https://www.youtube.com/watch?v=VBMGnAPfmsY)
 [![Итерирование, циклы и итераторы](https://img.youtube.com/vi/lq3b5_UGJas/0.jpg)](https://www.youtube.com/watch?v=lq3b5_UGJas)

Solutions/6-matrix.js

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+'use strict';
+
+const max = matrix => {
+  let value = matrix[0][0];
+  for (let i = 0; i < matrix.length; i++) {
+    const row = matrix[i];
+    for (let j = 0; j < row.length; j++) {
+      const cell = row[j];
+      if (value < cell) value = cell;
+    }
+  }
+  return value;
+};
+
+module.exports = { max };

Solutions/7-ages.js

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+'use strict';
+
+const ages = persons => {
+  const data = {};
+  for (const name in persons) {
+    const person = persons[name];
+    data[name] = person.died - person.born;
+  }
+  return data;
+};
+
+module.exports = { ages };